13444-10-5Relevant articles and documents
Mechanistic investigations into the photochemistry of 4-allyl-tetrazolones in solution: A new approach to the synthesis of 3,4-dihydro-pyrimidinones
Frija, Luis M. T.,Khmelinskii, Igor V.,Cristiano, M. Lurdes S.
, p. 3583 - 3591 (2007/10/03)
Photolysis (λ = 254 nm) of 4-allyl-tetrazolones 2a-c was carried out in methanol, 1 -propanol, 1-hexanol, acetonitrile, and cyclohexane. The sole primary photochemical process identified was molecular nitrogen elimination, with formation of pyrimidinones 6a-c. Following the primary photocleavage, secondary reactions were observed in acetonitrile and cyclohexane, leading to phenyl-isocyanate (7), aniline (9), and 1-phenylprop-1-enyl-isocyanate (10a). In alcoholic solutions, the primary products, 6a-c, remained photostable even under extended irradiation, making possible the isolation of 3,4-dihydro-pyrimidinones as stable compounds in very high yields. The observed photostability of pyrimidinones 6a-c in alcohols is ascribed to the excited state quenching via reversible proton transfer, facilitated by the solvent cage stabilization due to formation of hydrogen bonds. The viscosity of alcohols is directly related to the cage effects observed. The photocleavage of 4-allyl-tetrazolones leads probably to a caged triplet radical pair. This hypothesis is confirmed by the solvent viscosity effect on the photolysis quantum yields. Additionally, dissolved molecular oxygen sensitizes the formation of pyrimidinones, as should be expected for a triplet intermediate that can only form the product molecule after T-S conversion, which is accelerated by oxygen.
A kinetic investigation of the thermal rearrangement of allyloxytetrazoles to N-allyltetrazolones
Cristiano, M. Lurdes S.,Johnstone, Robert A. W.
, p. 489 - 494 (2007/10/03)
The mechanism of the thermal rearrangement of 1-aryl-5-allyloxytetrazoles 1 to give 1-aryl-4-allyltetrazolones 2 in very high yield has been investigated through kinetic studies in one polar and one less polar solvent. The results suggest mainly a concerted [3,3] sigmatropic process, in which a partially positively charged allyl group migrates from oxygen to nitrogen, similar to the polar transition state found in the Claisen rearrangement.
Photoextrusion of Nitrogen from 1,4-Dihydro-1-phenyl-5H-tetrazol-5-ones and -thiones. Benzimidazolones and Carbodiimides
Quast, Helmut,Nahr, Uwe
, p. 526 - 540 (2007/10/02)
Alkylation of 1-phenyltetrazolone 10a with 2-cyclohexen-1-yl bromide followed by dehydrogenation with 2,3-dichloro-5,6-dicyano-1,4-benzoquinone permits introduction of a phenyl group at N-4 of the tetrazole ring via the sequence 10a -> 10f -> 10g.The photoextrusion of molecular nitrogen from the (N-4)-substituted 1-phenyltetrazolones, 10a (hydrogen), 10b (methyl), 10d,e (propenyl), and 10g (phenyl) produces essentially quantitative yields of the corresponding benzimidazolones 14a,b,d,e,g.On irradiation of the 1-phenyltetrazolethiones 8b,f,g the carbodiimides 22b,f,g are obtained together with molecular nitrogen and sulfur, while 8a affords phenylcyanamide (25).In contrast to the thermolysis, which is known to give 2-(methylamino)benzothiazole (21b), photolysis of the (phenylimino)-1,2,3,4-thiatriazole 24, an isomer of methylphenyltetrazolethione 8b, also yields molecular nitrogen, sulfur, and methylphenylcarbodiimide (22b).